Tetrahedral Building Blocks Research Articles

CuAAC Synthesis of Tetragonal Building Blocks Decorated with Nucleobases

The CuAAC synthesis and the characterization of new rigid nucleobase-decorated tetrapodands exhibiting 1,3,5,7-tetraphenyladamantane and 9,9′-spirobifluorene central units are reported. 1,3,5,7-Tetraphenyladamantane and 3,3′,6,6′-tetrasubstituted 9,9′-spirobifluorene derivatives are tetrahedral building blocks, while the derivatives of 2,2′,7,7′-tetrasubstituted 9,9′-spirobifluorene can lead to 2D architectures.

Interpenetrated Frameworks with Anisotropic Pore Structures from a Tetrahedral Pyridine Ligand

Herein we investigate metal–organic frameworks (MOFs) employing the tetrahedral building block tetrakis(4-(pyridin-4-ylethynyl)phenyl)silane (1) as a structure-generating feature. Combining 1 with a series of different metal ions gives wildly different MOF topologies, porosities, and properties. The frameworks discussed deviate from the common construction principles of MOFs as both the ligand and the metal center impose their coordination geometry on the overall network. The resulting networks show attractive and unusual void distributions, yet with properly controlled transition metal ion geometries, these MOFs show a rational structural grammar with respect to their structures.

Novel Two-Dimensional Silica Monolayers with Tetrahedral and Octahedral Configurations

Free-standing and well-ordered two-dimensional (2D) silica monolayers with tetrahedral (T-silica) and octahedral (O-silica) building blocks are found to be stable by first principles calculations; T-silica is formed by corner-sharing SiO4 tetrahedrons in a rectangular network and O-silica consists of edge-sharing SiO6 octahedrons. Moreover, the insulating O-silica is the strongest silica monolayer, and can therefore act as a supporting substrate for nanostructures in sensing and catalytic applications. Nanoribbons of T-silica are metallic while those of O-silica have band gaps regardless of the chirality. We find the interaction of O-silica with graphene to be weak suggesting the possibility of its use as a monolayer dielectric material for graphene-based devices. Considering that the six-fold coordinated silica exists at high pressure in the bulk phase, the prediction of a small energy difference of O-silica with the synthesized silica bilayer together with the thermal stability at 1000 K suggest that synthesis of O-silica can be achieved in experiments.

Porous polymers based on aryleneethynylene building blocks.

Porous conjugated polymers are synthesized by metal-catalyzed coupling reactions. The progress for porous polymers when planar or tetrahedral building blocks are connected by alkyne units into novel materials is highlighted. The most prominent reaction for the buildup of the microporous alkyne-bridged polymers is the Sonogashira reaction, connecting alkynes to aromatic iodides or bromides. The availability of the building blocks and the potency of the Sonogashira reaction allow preparing a large variety of intrinsically porous polymeric materials, in which rigid struts connect multipronged centers. The microporous polymers are used as catalysts and as storage materials for gases and sensors. Postfunctionalization schemes, understanding of structure-property relationships, and the quest for high porosity are pertinent.

The First Covalent Organic Framework solved by Rotation Electron Diffraction

Covalent organic frameworks (COFs) represent an exciting new type of porous organic materials, which are constructed with organic building units via strong covalent bonds.[1] The structure determination of COFs is challenging, due to the difficulty in growing sufficiently large crystals suitable for single crystal X-ray diffraction, and low resolution and peak broadening for powder X-ray diffraction. Crystal structures of COFs are typically determined by modelling building with the aid of geometry principles in reticular chemistry and powder X-ray diffraction data. Here, we report the single-crystal structure of a new COF (COF-320) determined by 3D rotation electron diffraction (RED),[2] a technique applied in this context for the first time. The RED method can collect an almost complete three-dimensional electron diffraction dataset, and is a useful technique for structure determination of micron- and nanosized single crystals. To minimize electron beam damage, the RED dataset was collected at 89 K. 3D reciprocal lattice of COF-320 was reconstructed from the ED frames using the RED – data processing software[2]. As the resolution of the RED data only reached 1.6 Å, the simulated annealing parallel tempering algorithm in the FOX software package [3] was used to find a starting molecular arrangement from the 3D RED data. Finally, the crystal structure of COF-320 was solved in the space group of I-42d and refined using the SHELXL software package. The single-crystal structure of COF-320 exhibits a 3D extended framework by linking the tetrahedral organic building blocks and biphenyl linkers through imine-bonds forming a highly porous 9-fold interwoven diamond net.

Liquid acid-catalysed fabrication of nanoporous 1,3,5-triazine frameworks with efficient and selective CO2 uptake

New classes of nanoporous organic polymers based on 1,3,5-triazine units (NOP-1–6) were synthesized via a straightforward, methane-sulfonic acid-catalysed, cost-effective Friedel–Crafts reaction of 2,4,6-trichloro-1,3,5-triazine and tetrahedral building blocks. Among them, NOP-3 with a Brunauer–Emmet–Teller (BET) specific surface area up to 894 m2 g−1 and the total volume exceeding 0.41 m3 g−1 exhibits good hydrogen adsorption capacity (up to 1.14 wt% at 77 K/1.0 bar) and high carbon dioxide uptake (up to 11.03 wt% at 273 K/1.0 bar). Furthermore, it presents an effective selectivity for CO2 adsorption (NOP-6, CO2/N2 selectivity 38.7 at 273 K/1.0 bar), demonstrating potential applications in gas adsorption and separation.

1,3,5,7-Tetrakis(tetrazol-5-yl)-adamantane: the smallest tetrahedral tetrazole-functionalized ligand and its complexes formed by reaction with anhydrous M(II)Cl2 (M = Mn, Cu, Zn, Cd).

1,3,5,7-Tetrakis(tetrazol-5-yl)-adamantane (H4L) was probed as a building block for the synthesis of tetrazolato/halido coordination polymers with open-network structures. MCl2 (M = Cu, Cd, Zn, Mn) was reacted with H4L in DMF at 70 °C to yield [Cu4Cl4L(DMF)5]·DMF, ; [Cd4Cl4L(DMF)7]·DMF, ; [Zn3Cl2L(DMF)4]·2DMF, and [Mn2L(DMF)2(MeOH)4]·DMF·2MeOH·2H2O, . and (Fddd) are nearly isostructural and have zeolitic structures with a {4(3)·6(2)·8}, gis or gismondine underlying net, where the role of the tetrahedral nodes is served by the coordination bonded clusters and the adamantane moiety. (P21/n) has a porous structure composed of coordination bonded layers with a (4·8(2)) fes topology joined via trans-{Zn(tetrazolate)2(DMF)4} pillars with an overall topology of {4·6(2)}{4·6(6)·8(3)}, fsc-3,5-Cmce-2. (Pca21) is composed of stacked {Mn2L} hexagonal networks. In and the ligand fulfills a symmetric role of a tetrahedral building block, while in and it fulfills rather a role of an effective trigonal unit. Methanol-exchanged and activated displayed an unusual type IV isotherm with H2 type hysteresis for N2 sorption with an expected uptake at high P/P0, but with a smaller SBET = 505.5 m(2) g(-1) compared to the calculated 1789 m(2) g(-1), which is a possible result of the framework's flexibility. For H2 sorption 0.79 wt% (1 bar, 77 K) and 0.06 wt% (1 bar, RT) uptake and Qst = -7.2 kJ mol(-1) heat of adsorption (77 K) were recorded. Weak antiferromagnetic interactions were found in and with J1 = -9.60(1), J2 = -17.2(2), J3 = -2.28(10) cm(-1) and J = -0.76 cm(-1) respectively. The formation of zeolitic structures in and , the concept of structural 'imprinting' of rigid building blocks, and design opportunities suggested as a potential hexafunctionalized biadamantane building block.

A spin-frustrated cobalt(II) carbonate pyrochlore network

The crystal structure of the cobalt(II) carbonate-based compound cobalt(II) dicarbonate trisodium chloride, Co(CO(3))(2)Na(3)Cl, grown from a water-ethanol mixture, exhibits a three-dimensional network of corner-sharing {Co(4)(μ(3)-CO(3))(4)} tetrahedral building blocks, in which the Co(II) centres define a pyrochlore lattice and reside in a slightly distorted octahedral Co(O-CO(2))(6) environment. The space outside the hexagonal framework defined by these interlinked groups is occupied by Na(+) and Cl(-) ions. Antiferromagnetic coupling between adjacent Co(II) centres, mediated by carbonate bridges, results in geometric spin frustration which is typical for pyrochlore networks. The Co and Cl atoms reside on the special position 3, one Na atom on position 2 and a carbonate C atom on position 3.

Raman spectroscopy study of damage induced in fluorapatite by swift heavy ion irradiations

AbstractRaman spectroscopy was used to study the radiation damage of fluorapatite single crystals and sinters. Krypton and iodine ion irradiations were performed at high energies (∼1 MeV amu−1) for fluences ranging between 1 × 1011 and 5 × 1013 cm−2. Evolution of the symmetric stretching mode of the PO43− tetrahedral building blocks (strongest Raman mode observed at 965 cm−1) versus ion fluence was investigated. After irradiation, this peak decreases in intensity and a second broader peak appears at lower wavenumber. The well‐resolved peak has been assigned to the crystalline phase, and the broader one to the amorphous phase. The integrated intensity ratios of these two peaks versus fluence are in good agreement with the damage fractions determined by X‐ray diffraction (XRD). Fits of the amorphous fraction versus fluence show that the amorphization mechanisms is dominated by a single‐impact process for iodine ions and by a double‐impact process for krypton ions in the case of single crystals and sinters. For both irradiations, complete amorphization could not be obtained. The amorphous fraction saturates at a maximum value of 88% for sinters and 72% for single crystals. This is attributed to a recrystallization effect which is more important in single crystals than in sinters. For both types of samples, the crystalline peak shifts slightly to a lower wavenumber with fluence, and then shifts back to its initial value for an amorphous fraction larger than 60%. This feature is attributed to a stress relaxation, as shown in the XRD data, which is accompanied by a decrease of the crystalline peak full‐width at half‐maximum. Copyright © 2011 John Wiley & Sons, Ltd.

A “click-based” porous organic polymer from tetrahedral building blocks

A thermally and chemically stable “click-based” porous organic polymer with high surface area was synthesized from two tetrahedral building blocks.

Hybrid Zeolitic Imidazolate Frameworks with Catalytically Active TO4 Building Blocks

Crystalline porous materials with diverse chemical compositions (e.g., inorganic porous materials, inorganic–organic hybrid frameworks, and covalent organic frameworks) and framework topologies have been intensively studied in the past 60 years. They have wide applications in fields such as heterogeneous catalysis, gas storage, and separation. Moreover, some currently emerging areas related to health, energy use, and environmental conservation and remediation are still looking for the development of new porous materials. Zeolites are among the most well known porous materials because of their typical 4-connected open frameworks with TO4 (T= Si , Al, or P etc.) building blocks and outstanding catalytic or gas separation properties. Recently, the search for new zeolite-like structures was extended to metal–organic frameworks (MOFs), and these explorations in part produced a variety of zeolitic imidazolate frameworks (ZIFs) in which the tetrahedrally coordinated divalent cations (M=Zn or Co) are connected by the uninegative imidazolate ligands (im ). The rich chemistry associated with the organic imidazolate building blocks in ZIFs leads to some exceptional properties, such as large surface area and high gas uptake capacities. A question that emerges is: “Are there material with properties intermediate of those of zeolites and ZIFs?”. It is true that there is a hybrid state that remains unknown to date. In this work, we were seeking to integrate compositional and structural features of zeolites and ZIFs by combining TO4 tetrahedra with zinc–imidazolate units. Such a combination is trusted to bear both merits of zeolites and ZIFs, for example, possession of catalytic active TO4 sits of zeolites and high porosity of ZIFs. Herein, we report this kind of hybrid zeolitic imidazolate framework [denoted HZIFs; general formula: M4(im)6TO4] with catalytically active TO4 (T=Mo 6+ or W) building blocks and high thermal stability (up to 550 8C), which presents a new class of porous materials filling the gap between zeolites and ZIFs. The HZIFs reported herein are constructed from two kinds of tetrahedral building blocks and contain two kinds of connectivity, and combine structural features of both zeolites and ZIFs (Scheme 1). The TO4 units used in HZIFs are not traditional SiO4 or AlO4 units in aluminosilicate zeolites, but

Three-Dimensional Metal−Organic Frameworks Based on Tetrahedral and Square-Planar Building Blocks: Hydrogen Sorption and Dye Uptake Studies

Two three-dimensional metal-organic frameworks (MOFs) with tetraphenylmethane-derived tetracarboxylate linkers and copper paddle-wheel secondary building units were synthesized and characterized by single-crystal X-ray crystallographic studies. The two MOFs show a similar 4,4-connectivity but very different homocrossing and interpenetrating PtS network topologies and exhibit permanent porosity as probed by gas adsorption and dye inclusion experiments.

Generation of 2D and 3D (PtS, Adamantanoid) Nets with a Flexible Tetrahedral Building Block

The self-assembly of the flexible tetrahedral linker tetrakis[4-(carboxyphenyl)oxamethyl]methane acid with various transition metals (Cu, Co, and Mg) results in a 2D layered structure and 3D frameworks with PtS and adamantanoid topology. The PtS net exhibits permanent porosity, as confirmed by BET and gas adsorption experiments.

Hydrogen Bond-Mediated Self-Assembly of Polyhedral Oligomeric Silsesquioxane-Based Supramolecules

In this study, a functionalized pentaerythritol star polyester compound [tetrakis(nicotinoxymethyl)methane, TNMM] and an octakis[dimethyl(4-hydroxyphenethyl)siloxy]silsesquioxane (OP-POSS) were synthesized and used as tetrahedral and cubic building blocks, respectively, for three-dimensional, hydrogen-bond-mediated, polyhedral oligomeric silsesquioxane- (POSS-) based supramolecular network structures. With noncovalent chain extension of hydrogen bonds between its pyridine and phenol groups, the POSS-based supramolecular networks exhibited thermally reversible properties. Compared with the glass transition temperature of OP-POSS (ca. 20 °C) and the melting temperature of TNMM (ca. 70 °C), the hydrogen-bond-mediated miscible blend of 40 wt % TNMM in OP-POSS exhibited a single and higher glass transition temperature (37 °C). Because of its strong intermolecular hydrogen bonding, the dewetting pattern of the blend of 40 wt % TNMM in OP-POSS formed ringlike structures rather than the droplets formed by pure OP...

Micro and mesoporous metal–organic frameworks for catalysis applications

Micro and mesoporous metal-organic frameworks were synthesized using a single tetrahedral building block and their catalytic properties towards alkylation of toluene and biphenyl showed high selectivity for the para oriented product using these porous materials.

Interpenetrating metal-organic frameworks formed by self-assembly of tetrahedral and octahedral building blocks

To investigate the relationship between topological types and molecular building blocks (MBBs), we have designed and synthesized a series of three-dimensional (3D) interpenetrating metal-organic frameworks based on different polygons or polyhedra under hydrothermal conditions, namely [Cd(bpib) 0.5(L 1)] ( 1), [Cd(bpib) 0.5(L 2)]·H 2O ( 2), [Cd(bpib) 0.5(L 3)] ( 3) and [Cd(bib) 0.5(L 1)] ( 4), where bpib=1,4-bis(2-(pyridin-2-yl)-1 H-imidazol-1-yl)butane, bib=1,4-bis(1 H-imidazol-1-yl)butane, H 2L 1=4-(4-carboxybenzyloxy)benzoic acid, H 2L 2=4,4′-(ethane-1,2-diylbis(oxy))dibenzoic acid and H 2L 3=4,4′-(1,4-phenylenebis(methylene))bis(oxy)dibenzoic acid, respectively. Their structures have been determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric (TG) analyses. Compounds 1– 3 display α-Po topological nets with different degrees of interpenetration based on the similar octahedral [Cd 2(–COO) 4] building blocks. Compound 4 is a six-fold interpenetrating diamondoid net based on tetrahedral MBBs. By careful inspection of these structures, we find that various carboxylic ligands and N-donor ligands with different coordination modes and conformations, and metal centers with different geometries are important for the formation of the different MBBs. It is believed that different topological types lie on different MBBs with various polygons or polyhedra. Such as four- and six-connected topologies are formed by tetrahedral and octahedral building blocks. In addition, with the increase of carboxylic ligands’ length, the degrees of interpenetration have been changed in the α-Po topological nets. And the luminescent properties of these compounds have been investigated in detail.

Synthesis, Crystal Structures, and Thermal Properties of New [ZnX2(2,5‐dimethylpyrazine)] (X = Cl, Br, I) Coordination Compounds

AbstractEight new halidozinc(II) coordination compounds with 2,5‐dimethylpyrazine as a ligand were prepared. The reaction of ZnX2 (X = Cl, Br, I) and 2,5‐dimethylpyrazine in methanol results in the formation of catena‐(μ2‐2,5‐dimethylpyrazine‐N,N′)dichloridozinc(II) (1), catena‐(μ2‐2,5‐dimethylpyrazine‐N,N′)dibromidozinc(II) (3I and 3II), catena‐(μ2‐2,5‐dimethylpyrazine‐N,N′)diiodidozinc(II) (6), and diiodidobis(2,5‐dimethylpyrazine‐N)zinc(II) (7). In addition, in a solvent‐free reaction of ZnX2 (X = Cl, Br) and 2,5‐dimethylpyrazine,the ligand‐rich compounds bis(dichlorido)bis(2,5‐dimethylpyrazine‐N)(μ2‐2,5‐dimethylpyrazine‐N,N′)dizinc(II) (2), bis(dibromido)bis(2,5‐dimethylpyrazine‐N)(μ2‐2,5‐dimethylpyrazine‐N,N′)dizinc(II) (4), and dibromidobis(2,5‐dimethylpyrazine‐N)zinc(II) 2,5‐dimethylpyrazine solvate (5) were obtained. In the crystal structures of all compounds the zinc atoms are each coordinated by two halide atoms and two 2,5‐dimethylpyrazine ligands within a distorted tetrahedron. The zinc atoms in the ligand‐deficient 1:1 (1:1 = molar ratio of metal salt to ligand) compounds 1 and 6 and in the two polymorphic modifications 3I and 3II are linked by the N‐donor ligands into chains. In contrast, the crystal structure of the 2:3 compounds 2 and 4 are built up of oligomeric discrete [(ZnX2)2(2,3‐dimethylpyrazine)3] units in which each ZnX2 (X = Cl, Br) unit is coordinated by two halide atoms and one bridging and one terminal 2,5‐dimethylpyrazine ligand. The structures of the ligand‐rich 1:2 diiodido compound 7 and the 1:3 dibromido compound 5 consist of discrete monomeric tetrahedral building blocks. In the thermal decomposition reactions of the ligand‐rich compounds 2, 5, and 7, different mass steps are observed. In the first step, the ligand‐deficient 1:1 compounds 1 and 6 are formed in quantitative yields from 2 and 7, respectively, and 5 yields a mixture of 3I and 3II, and the second mass step leads to the formation of new ligand‐deficient 2:1 compounds. On further heating of the compounds, the remaining ligands are discharged. This results in the formation of the zinc(II) halides, which vaporize on further heating. Solvent‐mediated conversion experiments in methanol show that, irrespective of the ratio of zinc(II) halide and ligand, only the 1:1 compounds 1 and 3I are formed and therefore represent the thermodynamically most stable compounds at room temperature. For ZnI2 the 1:2 compound 7 is obtained at ratios of zinc(II) iodide to ligand larger than 1:3, whereas at lower ratios the 1:1 compound 6 is always obtained. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Assembly of a Chiral Bikitaite Zeolite Metal−Organic Framework Based on the Asymmetrical Tetrahedral Building Blocks

A novel chiral coordination polymer with a bikitaite zeolite framework has been constructed based on asymmetrical tetrahedral building blocks, in which the original chiralities derive from the configurational effect of benzotriazole ligands and transfer to the whole network through four distinct single helical chains.

Structures and Properties of Three Polymorphic Modifications based on Tetrahedral Building Blocks of Dichlorobis(pyridazine-N) Zinc(II)

Reaction of zinc(II) chloride with pyridazine under different conditions leads to the formation of three polymorphic modifications of dichlorobis(pyridazine-N) zinc(II). Forms I and II crystallize monoclinic in space group Cc (I) and P21/c (II), respectively, whereas form III crystallizes orthorhombic in space group Pna21. In all three forms, the zinc atoms are surrounded by two chloro atoms and two pyridazine ligands within distorted tetrahedra, and the orientations of the pyridazine rings within these tetrahedra are different. In the crystal structure, the tetrahedral building blocks are packed differently and are connected by intermolecular C–H···Cl and C–H···N interactions. Crystallization experiments clearly show that form I represents the thermodynamically most stable form at room temperature, whereas forms II and III are metastable. Theoretical calculations show that in form II the most stable molecular structure is found, whereas the molecular structure in form III is less stable by only 8 kJ/mol. Differential thermoanalysis and thermogravimetry measurements reveal that all forms decompose into a new ligand-deficient compound [ZnCl2(pyridazine)], which can also be prepared in solution. Form I can be transformed into form II, which is more stable at higher temperatures as evidenced by differential scanning calorimetry (DSC) measurements. On some of the DSC measurements, form I decomposes without further transformation into form II. Both forms I and II behave enantiotropic. The DSC thermogram of form III gave no indication of a polymorphic transformation.

Preparation of Stable and Metastable Coordination Compounds: Insight into the Structural, Thermodynamic, and Kinetic Aspects of the Formation of Coordination Polymers

The reaction of ZnI2 and pyrimidine in acetonitrile results in the formation of the 1:2 compound ZnI2(pyrimidine)2 (1), which consists of discrete tetrahedral building blocks. Slow heating of 1 at 1 degrees C/min leads to its transformation into the ligand-deficient intermediate 1:1 compound ZnI2(pyrimidine) (3), which upon further heating decomposes into the most ligand-deficient 2:1 compound (ZnI2)2(pyrimidine) (4). In contrast, the 2:3 compound (ZnI2)2(pyrimidine)3 (2) is formed as an intermediate by decomposing 1 using a faster heating rate of 8 degrees C/min. Compound 2 consists of oligomeric units in which each ZnI2 unit is coordinated by two iodine atoms and one bridging and one terminal pyrimidine ligand. The crystal structure of compound 3 is built up of ZnI2 units, which are connected by the ligands into chains. For the thermal transformation of 1 into 3 via 2 as the intermediate, a smooth reaction pathway is found in the crystal structure, for which only small translational and rotational changes are needed. The metastable solvated compound (ZnI2)(pyrimidine)(acetonitrile)0.25 (5) consisting of (ZnI2)4(pyrimidine)4 rings is obtained by quenching the reaction of ZnI2 and pyrimidine in acetonitrile using an antisolvent. On heating, 5 decomposes into a new polymorphic 1:1 compound 6, which consists of (ZnI2)(pyrimidine) chains. On further heating, 6 transforms into a third polymorphic 1:1 compound 7, which consists of (ZnI2)3(pyrimidine)3 rings, and finally into the 1:1 compound 3. Solvent-mediated conversion experiments reveal that compounds 1-4 are thermodynamically stable, whereas compounds 5-7 are metastable. Time-dependent crystallization experiments unambiguously show that compound 7 is formed by kinetic control and transforms within minutes into compound 6, which finally transforms into 3. Compound 3 represents the thermodynamically most stable 1:1 modification, whereas compounds 6 and 7 are metastable. The different compounds obtained by thermal decomposition and by crystallization from solution represent a snapshot of the species in solution and thus provide insight into the formation of coordination compounds.